(1) A
steeper roof that terminates into a flat
roof at its high point; (2) A type of roofing
containing two sloping planes of different
pitch on each of four sides. The lower plane
has a much steeper pitch than the upper,
often approaching vertical. Contains no
gables.

A thin
layer of woven, non-woven or knitted fiber
that serves as reinforcement to the material
or membrane.

MATERIAL SAFETY DATA SHEETS

A written
description of the chemicals within a product,
and pertinent other data including such
things as safe handling and emergency procedures.
In accordance with OSHA regulations, it
is the manufacturer's responsibility to
product an MADS and the employer's responsibility
to communicate its contents to employees.

A partially
enclosed rooftop structure used to aesthetically
conceal HVAC electrical or mechanical equipment
from view.

MECHANICALLY- FASTENED
MEMBRANES

Generally
used to describe membranes that have been
attached at defined intervals to the substrate.
Mechanical fastening may be performed with
various fasteners and/or other mechanical
devices, such as plates or battens.

MEMBRANE

(1) A
continuous flexible (or semi-flexible) roof
covering or waterproofing layer that forms
the water control element of a roofing system.
It is normally assembled on site from single
or multiple plies of material, e.g. polyvinyl
chloride roofing in single ply and bituminous
felt roofing in multiple ply; (2) A flexible
or semi-flexible roof covering or waterproofing
layer, whose primary function is the exclusion
of water; (3) A flexible or semi flexible
material, which functions as the waterproofing
component in a roofing or waterproofing
assembly, and whose primary function is
the exclusion of water.

MESH

The square
or circular opening of a sieve.

METAL FILM

A layer
of foil made from a single metallic substance
or form an alloy, that is laminated to a
membrane during manufacture. The metal foil
serves as the weathering surface of the
membrane or flashing material.

Unit of
length measurement in the metric system,
equal to 39.37 inches.

METRIC INFORMATION

Visualizing
Metric Measurements: Some basic comparisons
between the Imperial and metric systems
may assist in visualizing metric measurements.

• one millimeter
(mm) is about the thickness of a dime
• one meter (m) is about 3" longer
than a yardstick
• a 10 kilometer (km) race is about
6 miles
• a 175 yard, par 3 golf hole measures
160 meters (m)
• one square meter is the approximate
area of a desk top
• one roof square is approximately
9.3 square meters (m2)
• a roll of polymer modified roofing
weights about 30 kilograms (67 lb.)
• a 25-pound per square interply mopping
is 1.2 kilograms per square meter (kg/m2)

mg

Milligram

Mg

Megagram

mi

Mile

MICA DUST

Crystallized
complex slilicate materials that are pulverized
into dust form for use as a release agent.
See TALC.

MICROBIOLOGICAL RESISTANCE

The ability
of a material to resist attack and degradation
by various air- and soil-borne microorganisms.

MICRON

One millionth
(10-6) of a meter.

MIL

A unit
of measure; one mil is equal to 0.001 inches
or 25.400 microns, often used to indicate
the thickness of a roofing membrane.

MILLIMETER

(1) A
unit of thickness or length; 1,000 millimeters
= 100 centimeters = one meter; (2) A unit
of measure equal to one thousandth (0.001)
of a meter or 0.03937 inches.

A fine,
water-insoluble inorganic material, used
in a mixture with solid or semi solid bituminous
materials.

MINERAL SURFACED ROOFING

(1) Built-up
roofing materials whose top ply consists
of a granule surfaced sheet; (2) Roofing
materials whose sheet is coated on one or
both sides with asphalt and surfaced with
mineral granules; (3) A roofing sheet that
is coated on one or both sides with asphalt
and surfaced with mineral granules.

MINERAL-SURFACED SHEET

(1) A
felt that is coated on one or both sides
with asphalt and surfaced with mineral granules;
(2) Asphalt-saturated felt, coated on one
or both sides and surfaced on the weather-exposed
side with mineral granules.

mj

Megajoule

mm

Millimeter

MODEL CODES

A compilation
of standards or codes established to provide
uniformity in regulations pertaining to
building construction. Examples: ICBO (International
Conference of Building Officials); BOCA
(Buildings Officials an Code Administrators);
SBS (Standard Building Code).

MODIFIED BITUMEN

(1) A
bitumen modified through the inclusion of
one or more polymers (e.g., Atactic polypropylene,
styrene butadiene styrene, etc.); (2) Composite
sheets consisting of a polymer modified
bitumen often reinforced and sometimes surfaced
with various types of mats, films, foils
and mineral granules; (3) A broad class
of materials (and blends) that can be used
to change the performance characteristics
of a roofing grade asphalt.

MODIFIED BITUMEN ROOF COVERING

One or
more layer of polymer modified asphalt sheets.
The sheet materials shall be fully adhered
or mechanically attached to the substrate
or held in place with an approved ballast
layer.

MODULUS OF ELASTICITY

The ratio
of stress corresponding to strain (within
the elastic limit of a material); it is
a measure of the stiffness of a material.

MOISTURE CONTOUR MAP

A map
used to graphically defined the location
of moisture within a roof assembly after
a moisture scan has been performed.

MOISTURE RELIEF VENT

A venting
device installed through the roofing membrane
to relive moisture vapor pressure from within
the roofing system.

MOISTURE SCAN

The use
of a mechanical device (capacitance, infrared
or nuclear) to detect the presence of moisture
within a roof assembly. See NON-DESTRUCTIVE
TESTING.

MOLE RUN

A meandering
buckle or ridging in a roof membrane not
associated with insulation or deck joints.

MONOMER

(1) A
simple molecule that is capable of combining
with a number of like or unlike molecules
to form a polymer; (2) Class of molecules
with molecular weight ranging roughly between
30 and 250, capable of combining into huge,
polymeric macromolecules, 100 to 10,000
times as large as the basic monomeric molecules,
through chainlike repetition of the basic
monomeric chemical structure.

MOP-AND-FLOP

(1) An
application procedure in which roofing elements
(insulation boards, felt plies, cap sheets,
etc.) are initially placed upside down adjacent
to their ultimate locations, are coated
with adhesive, and are then turned over
and applied to the substrate; (2) An application
procedure in which roofing elements (insulation
boards, felt plies, cap sheets, etc.) are
initially placed upside down adjacent to
their ultimate locations, are coated with
adhesive or bitumen; and are then turned
over and applied to the substrate.

MOPPING

(1) The
process of applying hot bitumen with a mop
or mechanical applicator to the substrate
or to the felts of a built-up roof membrane;
(2) The application of hot bitumen, with
a roofer's hand mop or mechanical applicator,
to the substrate or to the felts of a bituminous
membrane.

Solid Mopping: A continuous
mopping of a surface, leaving no unmopped
areas. See SOLID MOPPING.

Spot Mopping: A mopping
pattern in which hot bitumen is applied
in roughly circular areas, generally about
an 18" diameter, leaving a grid of
unmopped, perpendicular bands on the roof.
See SPOT MOPPING.

Sprinkle Mopping:
A random mopping pattern in which heated
bitumen beads are strewn onto the substrate
with a brush, broom or mop. See SPRINKLE
MOPPING.

Strip Mopping:
A mopping pattern in which hot bitumen is
applied in parallel bands. See CHANNEL
MOPPING and STRIP MOPPING.

mph

Miles
Per Hour

MUD CRACKING

Surface
cracking of a material where the degraded
material appears similar to dried, cracked
earthen mud.